Composition-driven phase structures in laser-deposited titanium-steel composites: microstructural evolution and interfacial strengthening mechanisms

Combining titanium’s excellent corrosion resistance with steel’s low cost, titanium-steel composites have shown broad application prospects in marine equipment and petrochemical engineering. However, mismatches in thermophysical properties and intensive elemental interdiffusion in titanium-steel systems readily induce the formation of brittle intermetallic compounds at the interface during laser deposition, thereby limiting interfacial reliability. Clarifying the role of titanium alloy composition in regulating interfacial reaction pathways and interfacial performance is therefore critical. In this study, a Ti-10V-2Fe-3Al coating was designed and fabricated by laser deposition, with TA1(Pure-Ti) and Ti-6Al-4V coatings used as references. The effects of alloy composition on the thermal response, interfacial microstructural evolution, and interfacial strengthening behavior were systematically investigated. The Ti-10V-2Fe-3Al coating exhibited superior interfacial microstructural stability and mechanical performance, characterized by a continuous β-Ti matrix with uniformly dispersed nanoscale α-Ti, whereas the reference coatings were dominated by coarse α-Ti. A metallurgical transition zone of approximately 200 μm formed at all interfaces, within which FeTi and Fe2Ti were identified as the dominant intermetallic phases. First-principles calculations revealed that FeTi possesses lower formation enthalpy and more favorable lattice matching than Fe2Ti, while V stabilizes the BCC FeTi structure, suppressing brittle Fe2Ti formation. Consequently, the Ti-10V-2Fe-3Al coating achieved a shear strength of 101.5 MPa, representing a 107.5 % increase compared with the TA1 coating (48.9 MPa). These results demonstrate that β-stabilized titanium alloy design provides an effective strategy for regulating titanium–steel interfacial reactions and enhancing interfacial reliability.